Precoding Method, Transmitting Device, and Receiving Device

1. A reception method comprising: receiving a reception OFDM signal based on a plurality of precoded signals z 1 and z 2 with one or more antennas; demodulating the reception OFDM signal in accordance with a transmission scheme of the plurality of precoded signals z 1 and z 2 ; performing error-correction decoding on the demodulated signal; and acquiring audio data from the error-correction decoded signal, and externally outputting the audio data, wherein the plurality of precoded signals z 1 and z 2 are transmitted in the same frequency bandwidth at the same time, the plurality of precoded signals z 1 and z 2 are generated by (i) selecting one matrix from among N matrices F[i] by regularly hopping between the N matrices F[i] which are each selected at least once within a predetermined time period and (ii) multiplying the selected matrix by two baseband signals s 1 and s 2 that are represented by in-phase components and quadrature components, where N is an integer 1 or greater, and i is an integer from 0 to N−1, the N matrices F[i] are two-by-two matrices that satisfy a first condition, a second condition, and a third condition, the first condition is that x is an integer from 0 to N−1, y is an integer from 0 to N−1, and with respect to all x and all y satisfying x≠y, F[x]≠F[y] holds, the second condition is that x is an integer from 0 to N−1, y is an integer from 0 to N−1, and with respect to all x and all y satisfying x≠y, no real or complex number k holding F[x]=k×F[y] exists, the third condition is that the plurality of precoded signals z 1 and z 2 are calculated by multiplying the N matrices F[i] and the two baseband signals sl and s 2 , the N matrices F[i] satisfying Equation (1), F ⁡ [ i ] = 1 α 2 + 1 ⁢ ( ⅇ j ⁢ ⁢ θ 11 ⁡ ( i ) α × ⅇ j ⁡ ( θ 11 ⁡ ( i ) + λ ) α × ⅇ j ⁢ ⁢ θ 21 ⁡ ( i ) ⅇ j ⁡ ( θ 21 ⁡ ( i ) + λ + δ ) ) ( 1 ) where, α is a positive real number, θ 11 (i) and θ 21 (i) each indicate a phase rotation amount [radian] for a symbol number Ni, λ indicates a phase rotation amount [radian], δ indicates a phase rotation amount [radian], and j is an imaginary unit.

2. The reception method of claim 1 , further comprising detecting, from the reception OFDM signal, control information for notifying of the transmission scheme of the plurality of precoded signals z 1 and z 2 , wherein the demodulation of the reception OFDM signal is based on the control information.

3. The reception method of claim 1 , wherein the two baseband signals s 1 and s 2 are the same signals.

4. A reception apparatus comprising: an receiver that receives a reception OFDM signal based on a plurality of precoded signals z 1 and z 2 with one or more antennas; a demodulator that demodulates the reception OFDM signal in accordance with a transmission scheme of the plurality of precoded signals z 1 and z 2 ; a decoder that performs error-correction decoding on the demodulated signal; and an audio output that acquires audio data from the error-correction decoded signal, and externally outputs the audio data, wherein the plurality of precoded signals z 1 and z 2 are transmitted in the same frequency bandwidth at the same time, and the plurality of precoded signals z 1 and z 2 are generated by (i) selecting one matrix from among N matrices F[i] by regularly hopping between the N matrices F[i] which are each selected at least once within a predetermined time period and (ii) multiplying the selected matrix by two baseband signals sl and s 2 that are represented by in-phase components and quadrature components, where N is an integer 1 or greater, and i is an integer from 0 to N−1, the N matrices F[i] are two-by-two matrices that satisfy a first condition, a second condition, and a third condition, the first condition is that x is an integer from 0 to N−1, y is an integer from 0 to N−1, and with respect to all x and all y satisfying x≠y, F[x]≠F[y] holds, the second condition is that x is an integer from 0 to N−1, y is an integer from 0 to N−1, and with respect to all x and all y satisfying x≠y, no real or complex number k holding F[x]=k×F[y] exists, the third condition is that the plurality of precoded signals z 1 and z 2 are calculated by multiplying the N matrices F[i] and the two baseband signals s 1 and s 2 , the N matrices F[i] satisfying Equation (2), F ⁡ [ i ] = 1 α 2 + 1 ⁢ ( ⅇ j ⁢ ⁢ θ 11 ⁡ ( i ) α × ⅇ j ⁡ ( θ 11 ⁡ ( i ) + λ ) α × ⅇ j ⁢ ⁢ θ 21 ⁡ ( i ) ⅇ j ⁡ ( θ 21 ⁡ ( i ) + λ + δ ) ) ( 2 ) where, α is a positive real number, and β≠1, θ 11 (Ni) and θ 21 (Ni) each indicate a phase rotation amount [radian] for a symbol number Ni, λ indicates a phase rotation amount [radian], δ indicates a phase rotation amount [radian], and j is an imaginary unit.

5. The reception apparatus of claim 4 , further comprising a detector that detects, from the reception OFDM signal, control information for notifying of the transmission scheme of the plurality of precoded signals z 1 and z 2 , wherein the demodulator demodulates the reception OFDM signal based on the control information.

6. The reception apparatus of claim 4 , wherein the two baseband signals s 1 and s 2 are the same signals.